Takedown of the MAS 49 is very similar to that of the FN 49. Pull down on the little button in the back and hold it while pushing forward and pulling up on the receiver cover. Ease the receiver cover carefully off the gun (it is under spring pressure). Then pull the bolt carrier and bolt back to the dismount point and lift them out of the receiver. Reassemble in reverse order, taking care not to kink the recoil spring. That is about all that is needed for normal cleaning.
Clean well and clean out the gas tube if using corrosive ammo. There is a way to tell the French 7.5 corrosive from the non-corrosive, but I have forgotten it, so I assume 7.5 is corrosive.
The MAS semi autos date back to 1938 when they first started experiments using modified Model 1936 (bolt) rifles. There was a Model 1940, but the first to achieve any production was the Model 1944, which they worked on during the war. The Model 49 was basically an upgraded 1944 and the 1956 variation added all the goodies in the form of the grenade launcher, etc. Some features were "in the air" at the time the French started work, and turned up on the MAS designs as well as the FN 49, the Ljungman AB42, the FAL, etc. I think the MAS was the first rifle to use the gas tube system which later turned up on the Ljungman as well as on our own AR-15/M16. (But the French were smart enough to vent the gas into the air rather than through the bolt carrier.)
Jim